1. Field of the Invention
This invention relates to water purification systems and more particularly to multi-stage water purification systems that combine at least a plurality of a pre-filtration stage, ultraviolet light (UV) irradiation, ozone treatment and oxygenation stage, and a post-filtration stage.
2. Discussion of Prior Art
Water purification systems that combine filtration, UV irradiation and ozone treatment and oxygenation are known from U.S. Pat. Nos. 5,266,215, 5,540,848 and 5,709,799. These do not provide modular flexibility that permits adapting the system to particular, local water purification needs. In U.S. Pat. Nos. 5,266,215 and 5,540,848, for example, a single canister is described that combines filtration, the UV irradiation ozone and oxygenation treatment in a single chamber, but locates a filter in the UV, ozone, oxygenation chamber and so lessens the exposure of the water to the UV and ozone. Moreover, the system is not so versatile as to allow the user to adapt the system by choosing just one of pre-filtration, post-filtration or both in combination with UV irradiation and ozone treatment.
Introducing unfiltered water into UV irradiation can be ineffective when suspended particulates render the water so murky as to prevent the penetration of UV radiation. Also filters fine enough to collect bacteria on their surface have presented the problem that such bacteria breed there. A multi-stage purification system employing separately housed stages could be expected to be considerably more expensive than an all-in-one filtering, UV irradiating, ozone treating and oxygenation unit. Accordingly, there is a need for a water purification system and method that permits adaptation to existing conditions by separately housing a pre-filtration station, a UV irradiation and ozone treatment station and a post-filtration station, but that is carefully designed and constructed so as not to unreasonably increase the expense of manufacture.
In accordance with this invention there is provided a water purification system and method that, in addition to ultraviolet light irradiation, ozone treatment and oxygenation, provides such filtration as is required for the water that is available at a particular location. In this system, one canister defines a chamber for ultraviolet irradiation, ozone treatment and oxygenation and one or more other canisters provide one or more chambers for pre-filtration and/or post-filtration. As used here, xe2x80x9cpre-filtrationxe2x80x9d means filtering of water prior to its introduction to the location where ultraviolet irradiation occurs. xe2x80x9cPost-filtrationxe2x80x9d means filtering the water downstream from such location of ultraviolet irradiation treatment. xe2x80x9cPre-filterxe2x80x9d and xe2x80x9cpost-filterxe2x80x9d mean the filters used for pre-filtration and post-filtration, respectively.
Water quality and chemistry can vary dramatically for region to region. The three chamber integrated design of this invention allows use of the best available technologies in unique series to handle a wide range of localized water problems. A customized pre-filter can be installed to handle specific contaminants to be followed by ozonation, UV exposure (and resulting photo-catalytic oxidation) and carbon block filtration.
Individual chambers for, first, pre-filtration, second, ozone/UV oxygenation treatment and, third, post-filtration not only allow greater exposure to UV and ozone in the chamber devoted to that treatment, but permit the use of larger, more effective filters and allow the filtration to be chosen as desired to suit local conditions, or even eliminated if one of the filtration stages is not necessary. Where the available water is murky due to an abundance of particulates, pre-filtration clarifies the water. In the canister where the irradiation occurs (xe2x80x9cthe irradiation canisterxe2x80x9d), then, ultraviolet light can effectively treat the water without being blocked by the murkiness such particulates cause. Preferably, pre-filtration occurs in a canister defining a chamber in which a filter is located that eliminates almost all particulates larger than 5 microns in size. The filtering is xe2x80x9cnon-bypass.xe2x80x9d This means that every drop of water passing through the pre-filtration station is filtered prior to moving to the irradiation station. At the irradiation station, the entire elongate tubular ultraviolet lamp is exposed to the water moving along its length. The absence of any filter at this location means that the entire length of the lamp that is within the irradiation location contributes to ultraviolet irradiation. Ozone is produced in this location and that ozone is introduced into the water moving through the irradiation chamber.
The order of the technologies employed in accordance with the invention is quite important. In a preferred embodiment, a 5 micron polypropylene sediment filter is in the pre-filter chamber. If UV radiation is to be effective, the treated water must be optically clear to allow the UV radiation to pass through the water. If the water is cloudy, the UV radiation cannot pierce the cell membrane of bacteria and/or virus making it impossible to destroy its DNA and ability to reproduce. With pre-filtration this problem is overcome. As the water passes through the ozone/UV/advanced oxidation chamber, bacteria and virus are destroyed. The ozonated water then passes to the carbon block filter chamber. The filter removes any residual ozone, but not before it has had a chance to oxidize contaminants trapped on the outside layers of the carbon block. Each technology compliments the previous leaving completely sanitized and better tasting water.
The filters used can be common, commercially available filters. Ordinarily they are purchased separately and require installation. The three chamber system combines pre- and post-filtration into one, easy to install, easy to service system. Importantly, pre-filters can be selected to eliminate or substantially reduce specific contaminants prior to the UV irradiation, ozone, oxygenation and carbon block filtration processes. For example, some areas have a high degree of calcium, nitrates, arsenic, or fluoride. Pre-filters can be selected to remove these contaminants and installed in less than one minute.
A subsequent, post-filtration canister defines a chamber in which another finer filter is located. Again, the filtration is xe2x80x9cnon-bypass.xe2x80x9d This post-filtration filter may be a carbon block filter that removes particulates down to one micron in size. Because of effective irradiation and ozone treatment prior to post-filtration, bacteria collected on the surface of the post-filtration filter has been effectively killed and will not breed there.
The system may be a two or three canister system, depending on what filtration is required by local conditions. To limit the expense of the use of multiple canisters, a single molded exterior is used for every canister. This means only a single injection mold needs to be employed for the manufacture of the system. As for the interior, the molded canisters are similar, but the irradiation chamber of the irradiation canister is molded with a mold core that provides openings that are characteristic of this canister. One such opening is for the insertion and securing of the elongate ultraviolet lamp and a quartz cylinder that extend into and along the length of the chamber. Another opening accommodates a check valve leading to a venturi in the water flow path for drawing ozone past the check valve and into the water flow. A third opening accommodates a pressure sensor used to turn on the ultraviolet lamp when water pressure is present, as when a tap supplying the system is opened.
The similarity of the exteriors of the canisters means that they are interchangeably supported in a supporting frame adapted to hold two or more of the canisters.
The system combines five proven technologies into one convenient, easy to install, point-of-use device that produces quality drinking water directly from the tap. The efficient and compact system has been designed to install quickly either under a sink or directly to an existing faucet. The system can be installed to supply a water cooler.
The system of the invention is designed to be sold at competitive prices, but yet to be far superior to common water treatment equipment. This water purification system provides the consumer, in effect, with his or her own bottling plant, capable of producing unlimited quantities of pure water, with no waste or chemical byproducts, for pennies per day.
The system significantly reduces the level of harmful or nuisance contaminants commonly found in water supplies throughout the world. In particular, the system will substantially reduce or eliminate the following:
(1) Bacteria such as Shigella Dysenteriae, Vibrio Cholerac, E. Coli, and Salmonella. These are causes of serious and immediate illness such as dysentery and diarrhea which can lead to dehydration and are attributed to 24,000 childhood deaths each day.
(2) Viruses such as the Poliovirus, Hepatitis A, and Rotavirus, which can cause even more severe and debilitating illnesses.
(3) Larger parasitic organisms known as cysts, such as Giardia and Cryptosporidium. These are also causes of severe and persistent diarrhea and dysentery.
(4) Organic contaminants including many common fuels, pesticides and herbicides. These can have significant health ramifications and contribute to poor tasting water.
(5) Soluble and insoluble lead, which is present in water supplies to homes and offices with lead pipes, or copper pipes connected with lead solder.
(6) Chlorine, which contributes to poor taste, in high dosages combines to make carcinogenic trihalomethanes.
(7) Cancer causing trihalomethanes, which is a byproduct of the chlorination process.
The inventive system does not remove minerals that one""s body requires such as iron, calcium or magnesium, leaving water with its natural, spring-like flavor. In short, this system removes the harmful contaminants and bad tastes found in water supplies, but leaves in minerals that are important to good health.
Previously, canisters for water purification systems were often manufactured out of an extruded piece of plastic tubing. The extrusion would be cut to length, the exterior shape would be machined on a CNC lathe, and then female threads and o-ring grooves were machined in both the top and bottom of the chamber. Next, the canister had to be flame polished, which has a high rate of rejection for appearance. A silicon o-ring was installed in the bottom of the chamber. An injection molded bottom cap with male threads was threaded and sealed into the canister end. Another silicon o-ring was installed on the top of the chamber and an injection molded top cap with male threads was then threaded into and sealed to the top of the canister. This process was very expensive and time-consuming. Each system according to the present invention uses two canisters or three canisters. This, plus the cost of two or three molded bottom caps and two or three O-rings per canister, makes component costs per assembled unit represent more than 60% of the entire bill of materials for the system. By integrally molding the bottom cap and body this cost was significantly reduced and one possible leakage location was eliminated. The foregoing objects and advantages of the invention may be better understood from the following detailed description of one or more preferred embodiments when considered with the accompanying drawings.